The present invention relates to novel fungicide compositions useful in the treatment of fruits against fungal diseases, and the methods for treating fruits against fungal diseases using the said compositions.
It is well known that fruits, after they have been harvested, become covered with moulds, which causes them to rot.
These moulds appear after a long or shorter period, depending on the nature of the fruit or of the vegetable and the environmental conditions, and are the result of the development of one or more phytopathogenic fungi. These fungi, for the majority, and their mode of development are well known.
Thus, numerous methods for treating fruits have already been known and described.
Among them, there may be mentioned the application by immersion and/or brushing of the fruits after harvest in known fungicide solutions. Reference may be made, for example, to the work by A. Chitzanidis et al., Bulletin OEPP, 20(1), (1990), 163-168 or to that by E. Cohen et al., Phytoparasitica, 18(1), (1990), 17-26.
Other methods recommend a first treatment by spraying fungicide compounds on fruit trees, and then applying to the fruits other fungicides by immersion and/or brushing. This type of treatment is described in particular by S. Toker et al., Turk. J. Agric. For., 20(1), (1996), 78-83.
Among the fungicides most commonly used for the treatment of fruits after harvest, there may be mentioned imazalil (described in xe2x80x9cThe Pesticide Manualxe2x80x9d, 10th edition, British Crop Protection Council, page 580), thiabendazole (ibid. page 972) or SOPP (sodium o-phenylphenate, ibid. page 794), which have so far proved the most effective.
These compounds are indeed particularly active against strains of Penicillium, which are responsible for numerous fungal diseases.
Unfortunately, strains of Penicillium resistant to thiabendazole (P. R. Harding Jr., Plant Dis. Rep., 56(3), (1972), 256-260), and more recently resistant to imazalil have appeared (see for example the publications by J. W. Eckert, Phytopathology, 77(12), (1987), 1728, and ISPP Chemical Control Newsletter, 10, (1988), 36-38).
These compounds are moreover weakly active, or even inactive on other phytopathogenic fungi. In addition, while imazalil may be used for preventive and curative treatment, this curative effect remains limited over time.
It is also always desirable to improve the fungicide products used for treating fruits.
It is also always desirable to reduce the doses of chemical products applied to fruits, in particular by reducing the doses for application of the products.
It is finally always desirable to increase the range of antifungal products available so as to find among them those best suited to specific uses.
A first object of the present invention consists in providing fungicide compositions exhibiting a broad activity spectrum, that is to say possessing substantial activity on a number of phytopathogenic fungi greater than the number of phytopathogenic fungi treated with known compositions.
A second object of the invention consists in providing fungicide compositions possessing both a preventive effect and a curative effect, in particular an improved curative effect compared with the fungicide compositions currently used.
Another object of the present invention consists in providing fungicide compositions which are able to effectively control the strains of fungi resistant to known fungicide compositions.
Another aim of the present invention is to provide fungicide compositions which are effective at substantially lower doses compared with the doses currently applied.
Another object of the present invention consists in providing fungicide compositions applied to fruits so as to prevent or delay their rotting, while remaining suitable for consumption.
Other objects of the invention will appear in the disclosure of the invention which is presented in the remainder of the present description.
Surprisingly, it has been discovered that all these objects are achieved fully or partially by virtue of the fungicide compositions which are the subject of the present invention.
The present invention therefore relates to fungicide compositions useful for controlling phytopathogenic fungi infesting or capable of infesting fruits, characterized in that they contain:
at least one fungicide compound inhibiting mitochondrial respiration, and
at least one fungicide compound inhibiting sterol biosynthesis.
Among the fungicide compounds inhibiting mitochondrial respiration there may be mentioned, for example, strobilurin and analogous compounds or derivatives, such as for example azoxystrobin, kresoxim-methyl, trifloxystrobin, picoxystrobin, discostrobin, but also 4-chloro-2-cyano-N,N-dimethyl-5-p-tolylimidazole-1-sulphonamide, 5-methyl-5-(4-phenoxyphenyl)-3-(phenylamino)-2,4-oxazolidine-dione (or famoxadone) as well as the compounds of general formula (I): 
in which:
M represents an oxygen or sulphur atom;
n is an integer equal to 0 or 1;
Y is a fluorine or chlorine atom, or a methyl radical.
The compounds of formula (I) are known, in particular by patent application EP-A-0 629 616.
Preferably, there will be chosen from the compounds of formula (I) the compound for which M represents a sulphur atom and n is equal to 0, that is to say (4-S)-4-methyl-2-methylthio-4-phenyl-1-phenylamino-2-imidazoline-5-one, called Fenamidone.
The list of fungicide compounds inhibiting mitochondrial respiration should not be considered as being limiting, but as illustrating, for persons skilled in the art, the range of compounds inhibiting mitochondrial respiration available to them.
Likewise, by way of illustration, among the compounds inhibiting sterol biosynthesis which may be used in the fungicide compositions of the present invention, there may be mentioned, for example, imazalil.
Preferably, there will be chosen, for the fungicide compositions which are the subject of the invention, as inhibitor of mitochondrial respiration, a compound of formula (I) or famoxadone, and as inhibitor of sterol biosynthesis, imazalil.
Most preferably, the fungicide compositions according to the present invention comprise imazalil in combination with fenamidone.
The compositions according to the present invention are provided in the form of liquids which are viscous to a greater or lesser degree, ranging from a viscosity similar to that of water or of oil, to wax-type formulations.
As a general rule, the doses of fungicide compounds present in the compositions of the invention depend on the nature of the compounds themselves, the nature of the fruits to be treated and the nature of the diseases to be treated and their degree of infestation.
The doses of inhibitors of mitochondrial respiration used for the fungicide compositions of the present invention are advantageously between 10 mg/l and 1000 mg/l, preferably between 20 mg/l and 300 mg/l, preferably still between 40 mg/l and 150 mg/l, for example between 50 mg/l and 100 mg/l.
The doses of inhibitors of sterol biosynthesis used for the fungicide compositions of the present invention are advantageously between 100 mg/l and 3000 mg/l, preferably between 50 mg/l and 2500 mg/l, preferably still between 200 mg/l and 2000 mg/l, for example between about 400 mg/l and 1000 mg/l.
It is clearly understood that the fungicide compositions according to the present invention may contain, in addition to one or more inhibitors of mitochondrial respiration and one or more inhibitors of sterol biosynthesis, one or more other fungicide compounds known to persons skilled in the art and suitable for treating fungal diseases of fruits.
By way of nonlimiting example, the other fungicide compounds which may be included in the compositions of the invention comprise phosphorous acid, as well as its derivatives and its salts. A product which is most particularly suitable for the compositions of the present invention is the aluminium salt of phosphorous acid, called Fosetyl-Al (described in xe2x80x9cThe Pesticide Manualxe2x80x9d, 10th edition, British Crop Protection Council, page 530).
Thus, a most particularly preferred composition of the present invention comprises imazalil, fenamidone and fosetyl-Al.
The doses of these other fungicide compounds which may be added to the compositions according to the present invention depend on the types of diseases to be treated, their degree of infestation, the nature of the fruits to be treated and the actual nature of these compounds. Persons skilled in the art will know how to assess the doses to be applied which may be for example between 500 mg/l and 6000 mg/l, for example between 2000 mg/l and 4000 mg/l.
When fosetyl-Al is used, the dose for use is generally between 1000 mg/l and 1500 mg/l, preferably about 1200 mg/l.
It has therefore been discovered, surprisingly, that the addition of an inhibitor of mitochondrial respiration to an inhibitor of sterol biosynthesis substantially increases the activity spectrum of the fungicide compositions and possesses in particular an unexpected efficacy on the strains of phytopathogenic fungi resistant to the inhibitors of sterol biosynthesis.
Thus, the fungicide compositions according to the invention are effective for treating the majority of phytopathogenic fungi infesting or capable of infesting fruits, and in particular:
Phytophthora spp., for example brown rot of citrus fruits (Phytophthora parasitica), and gummosis of citrus (Phytophthora citrophthora);
Penicillium spp., for example blue mould (Penicillium italicum), and green mould (Penicillium digitatum);
bitter rot of citrus fruits (Geotrichum candidum);
black rot of citrus fruits (Alternaria citri);
anthracnose (Colleotrichum gloeos-porioides);
melanose or phomopsis rot (Diplodia natalensis or Phomopsis citri).
Other phytopathogenic fungi may also be controlled using the fungicide compositions of the invention. The nature of these other fungi partly depends on the nature of the other fungicides present in the compositions which are the subject of the invention.
The fruits which may be treated with the compositions according to the invention are of any type, and particularly those which may be damaged by the appearance of phytopathogenic fungi which are described above, in particular during prolonged storage of the said fruits.
Furthermore, the compositions according to the invention find a particularly advantageous use in the treatment of fruits after harvest, in order to prevent or delay their rotting, while remaining fit for consumption.
Thus, among the fruits which may be treated with the fungicide compositions of the invention, there may be mentioned in particular citrus fruits, for example lemons, oranges, grapefruits, citron fruit, clementines, mandarins, and the like.
It thus appears that the field of application of the fungicide compositions described here is not limited, and that these compositions may be used in all types of cases where protection or action against fungal attacks is needed in order to prevent or stop the rotting of edible fruits.
The compositions according to the invention comprise, in addition to the fungicide compounds described above, solid or liquid carriers which are acceptable in the fungal treatment of fruits and/or surfactants which are also acceptable in the fungal treatment of fruits. In particular, there may be used inert and customary carriers and customary surfactants. These compositions cover not only compositions ready to be applied to the fruits to be treated by immersion or using a suitable device, but also the commercial concentrated compositions which have to be diluted before application to the fruits.
These fungicide compositions according to the invention may also contain any sort of other ingredients such as, for example, protective colloids, adhesives, thickeners, thixotropic agents, penetrating agents, stabilizers, sequestrants, texturing agents, flavouring agents, taste enhancers, sugars, sweeteners, colorants and the like. More generally, the active substances may be combined with any solid or liquid additives corresponding to the usual formulation techniques.
In general, the compositions according to the invention usually contain from 0.05 to 95% (by weight) of active substance (the expression active substance is understood here to mean all the fungicide compounds contained in the present formulation), one or more solid or liquid carriers and, optionally, one or more surfactants.
The term xe2x80x9ccarrierxe2x80x9d, in the present disclosure, denotes a natural or synthetic organic or inorganic substance with which the active substance is combined to facilitate its application to fruits. This carrier is therefore generally inert and should be acceptable in the agri-foodstuffs sector. The carrier may be solid (clays, natural or synthetic silicates, silica, resins, waxes, solid fertilizers, and the like) or liquid (water, alcohols, in particular butanol, and the like).
The surfactant may be an emulsifying agent, a dispersing agent or a wetting agent of the ionic or nonionic type or a mixture of such surfactants. There may be mentioned, for example, salts of polyacrylic acids, salts of lignosulphonic acids, salts of phenolsulphonic or naphthalenesulphonic acids, polycondensates of ethylene oxide with fatty alcohols or with fatty acids or with fatty amines, substituted phenols (in particular alkylphenols or arylphenols), salts of esters of sulphosuccinic acids, derivatives of taurine (in particular alkyl taurates), phosphoric esters of polyoxyethylated phenols or alcohols, esters of fatty acids and polyols, sulphate, sulphonate and phosphate functional group-containing derivatives of the above compounds. The presence of at least one surfactant is generally essential when the active substance and/or the inert carrier are not soluble in water and when the vector agent for application is water.
Accordingly, the compositions according to the invention may contain the active substance in very broad limits, ranging from 0.05% to 95% (by weight). Their content of surfactant is advantageously between 0.5% and 40% by weight. Unless otherwise stated, the percentages given in this description are percentages by weight.
These compositions according to the invention are themselves in fairly diverse, solid or liquid, forms.
As solid composition forms, there may be mentioned dustable powders (content of active substance which may be up to 100%) and granules, in particular those obtained by extrusion, by compacting, by impregnation of a granulated carrier, by granulation using a powder as starting material (the content of active substance in these granules being between 0.5 and 80% for these latter cases). Such solid compositions may be optionally used in the form of a liquid which is viscous to a greater or lesser degree, depending on the type of application desired, for example by diluting in water.
As liquid composition forms or forms intended to constitute liquid compositions during application, there may be mentioned solutions, in particular water-soluble concentrates, emulsions, suspension concentrates, wettable powders (or spraying powder), oils and waxes.
The suspension concentrates, which can be applied by spraying, are prepared so as to obtain a stable fluid product which does not form a deposit and they usually contain from 10 to 75% of active substance, from 0.5 to 15% of surfactants, from 0.1 to 10% of thixotropic agents, from 0 to 10% of appropriate additives, such as antifoams, corrosion inhibitors, stabilizers, penetrating agents and adhesives and, as carrier, water or an organic liquid in which the active substance is not or not very soluble: some organic solids or inorganic salts may be dissolved in the carrier to help prevent sedimentation or as antigels for water.
By way of example, here is a suspension concentrate composition: